This invention relates to compositions and methods for saturating paper to provide desirable properties such as water resistance, wet strength, flexibility, softness, durability, fold resistance, drapability, in products such as wallpaper, book covers, map and label stock.
Many currently available paper products are saturated in production to provide the above properties. For wallpaper, strippability is also an important feature. Typically, the paper is saturated with a latex emulsion, after which other treatments such as ground coating, printing, and scrubb-resistant resin coatings are applied. Typically, the latex used to saturate such papers is provided as an emulsion, e.g. of a latex such as styrene butadiene (SBR), polyvinyl acetate, a vinyl acrylic, an ethylene vinyl acetate, or an acrylic emulsion. Such latices are impervious to water when dried and/or cured. Fig. 1 shows in highly diagrammatic form the various layers of a strippable latex-saturated wallpaper.
Processes involving latex treatment of paper have an inherent disadvantage because the latex generally cannot be removed from the treated paper, and, therefore, the treated paper cannot be repulped/recycled. If there is a production reject or a difficulty requiring stoppage, a large volume of unusable paper must be discarded, e.g. to a landfill, contributing to a significant environmental problem. Latices also present serious difficulties with expensive felts and wires used in paper making. Specifically, use of latex is likely to cause spots or sticky areas on felts or wires, which cause problems in cleaning the felts. It is common to produce latex-treated papers in short runs to reduce the amount of paper that is wasted if a run is outside specification or if other problems are encountered.
Stauntson et al. U.S. Pat. No. 3,574,656 disclose a ground-coated wallpaper with a removable washable surface coating of alkyl acrylate (and/or methacrylate) in combination with vinylidene chloride copolymer. Various other monomers may be present.